Table 2.

Antimicrobial cystatin C pharmacokinetic study

Drug	Study	Population			Analytical methods			Renal function		Renal function-PK
		Number of patients	Patients	Age range (years)	Creatinine	CysC	Drug	GFR based on creatinine	GFR based on CysC	Significant correlation between CysC and drug clearances (r2)	Significant correlation between CysC and drug C0 (r2)	CysC is better correlated with PK compared to creatinine (r2)
Vancomycin	Chen et al. 30	65	Adult and elderly patients	19–78	Enzymatic	PETIA	FPIA	Creatinine clearance*	Flodin†	Yes (0.85)	―	Yes (0.64)
	Tanaka et al. 54	60	Adult patients	16–64	―	PENIA	―	CG¶¶	Hoek‡	―	Yes (0.78)	Yes (0.54)
		105	Elderly patients	66–95	―	PENIA	―	CG	Hoek	―	Yes (0.79)	Yes (0.18)
	Kees et al. 31	25	Critically ill adults and elderly patients	31–82	Enzymatic	PENIA	HPLC	CG	Hoek	Yes (0.70)	―	Yes (0.37)
	Suzuki et al. 32	18	Adult patients	―	Enzymatic	PENIA	FPIA	CG/ MDRD§	Rules¶/Hoek	―	Yes (0.42/0.49)	Yes (0.13/0.19)
	Tanaka et al. 33	164	Adult and elderly patients	17–95	―	PENIA	FPIA	―	Hoek	Yes (0.84)	―	―
	Okamoto et al. 34	24	Elderly patients	66–87	Enzymatic	PETIA	FPIA	CG	Larsson**	Yes (0.78)	―	Yes (0.47)
	Chung et al. 35	678	Adult and elderly patients	18–96	Jaffé	PETIA	FPIA	CG	Concentration	Yes	―	Yes
Amikacin	Halacova et al. 36	71	Adults and children with cystic fibrosis	4–28	Enzymatic	PETIA	FPIA	CG / Schwatz††	Grubb‡‡/Larsson	Yes	―	Yes
Cefuroxime	Viberg et al. 37	97	Adult patients	24–95	Enzymatic	PENIA	HPLC	Concentration	Concentration	―	Yes	Yes
Arbekacin	Otsuka et al. 38	95	Adult and elderly patients	73–16	Enzymatic	PENIA	FPIA	CG	Sjöström§§	―	Yes (0.89)	Yes (0.64)

CG, Cockcroft–Gault equation

CysC, cystatin C

FPIA, fluorescence polarization immunoassay

HPLC, high-performance liquid chromatography

MDRD, modification of diet in renal disease equation

PENIA, particle-enhanced nephelometric immunoassay

PETIA, particle-enhanced turbidimetric immunoassay.

^*Creatinine clearance = creatinine concentration in urine x urine flow rate / plasma creatinine concentration.

^†Flodin equation: eGFR = 79.901 × CysC^–1.4389.

^‡Hoek equation: eGFR = (80.35 / CysC) – 4.32.

^§MDRD equation: eGFR = 186.3 × (creatinine / 88.4) ^–1.154 × age^–0.203 × 0.742 (if female) × 1.21 (if African).

^¶Rules equation: eGFR = 66.8 × CysC ^–1,3.

^**Larsson equation: eGFR = 99.43 × CysC^–1.5837.

^††Schwartz equation: eGFR = k × height / serum creatinine; the value of k varies as a function of age and gender being 0.33 in preterm infants, 0.45 in term infants, 0.55 in child or adolescent girls and 0.7 in adolescent boys.

^‡‡Grubb equation: eGFR = 84.69 × CysC^–1.68 × 1.384 (if a child <14 years).

^§§Sjöström equation eGFR = (124 / CysC) – 22.3.

^¶¶Cockroft–Gault: eGFR= k × weight × (140 – age) / creatinine; the value of k is 1.23 for men and 1.04 for women.